JP2008063101A - Paper carrying method, and document reader using the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper carrying method improved in users' convenience in post-processing after occurrence of double feed of paper. <P>SOLUTION: The paper carrying method comprises: supplying paper sheets loaded in a paper feed part to a paper carrying passage; determining whether double feed occurs in the paper sheets carried to the paper carrying passage or not; discharging, when no double feed is determined, the paper sheets to a paper discharge part by a discharge roller after executing predetermined processing to the paper sheets; and continuing, when occurrence of double feed is determined, the carrying of the paper sheets as in a double feed state without executing the predetermined processing to the paper sheets to discharge the paper sheets to the discharge part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sheet conveying method and a document reading apparatus using the method, and more particularly, a sheet conveying method and a document reading apparatus using the method for improving convenience with respect to post-processing of a sheet having undergone double feeding. About.

As a conventional technique related to the present invention, an accurate double feed detection is performed in a double feed detection device that detects double feed of paper using an ultrasonic sensor composed of a pair of transmitters and receivers. In order to avoid the influence of unnecessary reflected waves in the vicinity of the ultrasonic sensor installation location, which is a cause of obstruction, there is known one in which a sound absorbing material is arranged around the transmitter and the receiver (see, for example, Patent Document 1). .
JP-A-2005-82350

In recent years, high-speed printing of image forming apparatuses such as copying machines and printers has been promoted.
For this reason, it is required to transport a document as a sheet at a high speed also to a sheet through device (SPF) (single-pass feeder) which is mounted on an image forming apparatus and has a function of reading an image of a document by a document moving method. It has been.
However, if the document is to be transported at high speed, when the document is fed from the SPF paper feeding unit on which the document is loaded to the sheet transport path, the sheet is likely to be charged with static electricity, and the document may be fed in a double feed state in which the documents overlap. Becomes higher.

When the document is conveyed in the double feed state in which the originals are overlapped and the image is read by the image reading unit, an image different from the image that should be read is naturally read.
Therefore, in the conventional SPF with a double feed detection function, when a double feed of a document is detected, the conveyance of the document is immediately stopped, and a message indicating that a document jam (JAM) has occurred is displayed to the user. The user was requested to remove the document in the paper transport path.
When the SPF cover or the like is opened by the user and the paper in the paper transport path is removed, in order to align the arrangement order with the documents that have already been read normally, Please return it to the user "message and request the user to return the XXth document to the paper feeder as instructed.

If the user understands the instructions of the message accurately and returns the XXth document to the paper feed unit and makes a read request again, conveyance and image reading start again from the document returned to the paper feed unit. Thus, the arrangement order with the previously read document is matched.
However, in the SPF that transports a document at a high speed as described above, not only a document that is in a double feed state but also other documents that have been sent out in advance often exist on the paper transport path.
At this time, it is difficult for the user to immediately determine which of the originals whose conveyance has been stopped in the paper conveyance path has been normally read. Even if you are instructed to "Return to the Department", it is difficult to understand exactly which manuscript should be returned, and it is often confusing.

Further, when the user opens the SPF cover or the like and removes a document stopped in the paper transport path, the document stopped in the paper transport path may be sandwiched between transport rollers provided along the paper transport path. In many cases, the original may be damaged when the original is removed.
If the document is damaged, it is a matter of course that the image reading originally requested by the user cannot be performed, which causes a great deal of damage to the user.

  The present invention has been made in consideration of the above circumstances, and is a paper transport method for improving user convenience regarding post-processing after double feeding of paper, and original reading using the method. A device is provided.

  The present invention feeds the paper stacked in the paper feeding unit to the paper transport path, determines whether or not the multi-feed has occurred in the paper fed to the paper transport path, and determines that the multi-feed has not occurred. If it is determined, a predetermined process is performed on the paper, and then the paper is discharged to the paper discharge unit by the paper discharge roller. If it is determined that double feeding has occurred, the predetermined process is not performed on the paper. In addition, the present invention provides a paper transport method for continuously transporting paper in the double feed state and sending it to the paper discharge unit.

According to the present invention, when it is determined that the sheet fed to the sheet conveyance path is double-fed, the sheet is continuously conveyed in the double-fed state without performing a predetermined process for the sheet. Therefore, it is possible to easily discriminate a sheet that has been conveyed in a double feed state without executing a predetermined process, and it is convenient for the user regarding post-processing after the double feed of the paper has occurred. Can be improved.
Furthermore, it is possible to eliminate the inconvenience of causing the user to remove the paper from the paper transport path due to the double feeding of the paper.

  The paper transport method according to the present invention feeds the paper stacked in the paper feed unit to the paper transport path, determines whether or not the multi-feed has occurred in the paper fed to the paper transport path, If it is determined that the sheet has not occurred, a predetermined process is performed on the sheet, and then the sheet is discharged to the sheet discharge unit by the discharge roller. If it is determined that the double feed has occurred, the predetermined process is performed on the sheet. In this case, the sheet is continuously conveyed in the double feed state without being executed, and sent to the paper discharge unit.

In the paper transport method according to the present invention, the paper feed unit means a portion on which paper to be transported is stacked. For example, in a sheet through device mounted on a copying machine, a facsimile, a scanner, or the like, a document tray In an image forming apparatus such as a copying machine, a facsimile machine, or a printer, a paper feed cassette may be used. Needless to say, a manual feed tray of a sheet through device or an image forming apparatus is also included in the category of the paper feeding unit.
The paper means a document on which an image to be read is formed, a recording paper on which the read image is formed, an OHP sheet, and the like.
The paper transport path means a portion that guides the paper fed from the paper feeding unit along a predetermined path.

The double feeding of the sheets means that at least a part of the plurality of sheets are conveyed without being separated and conveyed one by one.
Predetermined processing means any processing on a sheet. For example, an image reading process at a predetermined reading position in a sheet through apparatus, an image forming process in an image forming unit in an image forming apparatus, and the like. Can be mentioned.
The paper discharge unit means a portion that receives the paper discharged from the paper transport path, and includes, for example, a paper discharge tray in a sheet-through apparatus or an image forming apparatus.

In the paper transport method according to the present invention, when it is determined that double feeding has occurred, paper feed from the paper feed unit to the paper transport path may be stopped.
According to such a configuration, when it is determined that double feeding has occurred, paper feeding from the paper feeding unit to the paper transport path is stopped, so that the user is transported in the double feeding state and sent to the paper discharge unit. By returning the received sheets to the sheet feeding unit, the arrangement order with the unconveyed sheets remaining in the sheet feeding unit can be easily recovered.

In addition, the paper transport method according to the above configuration in which the paper feeding is stopped when it is determined that the multi-feed occurs, the paper that has been transported in the double feed state is sandwiched between the paper discharge rollers, The sheet may be held in a state.
According to such a configuration, since the paper in the double feed state is sandwiched and held in the state by the paper discharge roller, the user transports the paper that has been transported in the double feed state and has not been subjected to the predetermined processing to the predetermined paper. It can be easily and reliably distinguished from other papers that have been processed and previously discharged to the paper discharge unit, and are extremely convenient for the user.

In the paper transport method according to the present invention, when it is determined that double feeding has occurred in the fed paper, and the paper fed before the paper in which double feeding has occurred is present in the paper transport path, A predetermined process may be performed on the previously fed paper and the paper may be discharged to the paper discharge unit.
According to such a configuration, since the previously fed paper is discharged to the paper discharge unit after predetermined processing is executed, the user can easily determine only the paper that has been conveyed in the double feed state. Even if there are a plurality of sheets in the sheet conveyance path in order to convey the sheet at a high speed, the above-described effects of the present invention can be obtained.

  From another point of view, the present invention is a document reading apparatus using the above-described sheet conveying method according to the present invention, in which a sheet feeding unit on which documents are stacked, and a document loaded on the sheet feeding unit are disposed on a sheet conveying path. A paper feed roller that feeds the paper to the paper transport path, a double feed detection means that detects double feed of the original when the originals are overlapped and fed to the paper transport path, and An image reading means for reading an image, a paper discharge roller for discharging a document to a paper discharge section, a paper feed roller, a double feed detection means, an image reading means, and a control section for controlling the paper discharge roller. The document feed roller is driven to feed the document to the paper transport path, and it is determined by the multi-feed detection means whether or not the document fed to the paper transport path is double-feeded. If it is determined that the image is read, the image reading unit executes image reading of the document and discharges the document. If the document is discharged to the paper output unit by driving the printer and it is determined that double feeding has occurred, the document will continue to be conveyed in the double feed state without causing the image reading means to read the original image. Thus, a document reading device that sends the document to the paper discharge unit is also provided.

According to the above document reading apparatus of the present invention, when the control unit determines that double feeding has occurred in the document, the document is continued to be conveyed in the double feeding state without performing image reading of the document. In addition to being able to prevent erroneous image reading in advance, it is easy to identify documents that have been transported in the double feed state without being read and sent to the paper discharge unit. In addition, it is possible to improve the convenience of the user regarding the post-processing of the document in which double feeding has occurred.
Furthermore, it is possible to eliminate the inconvenience of causing the user to remove the original from the paper conveyance path due to the double feeding of the paper.

In the document reading apparatus according to the present invention, the paper feed roller is a roller that basically sends a document to the paper transport path by applying a frictional force to the document stacked on the paper feed unit in the paper transport direction. Although it means, for example, a pickup roller and a separation roller that applies a frictional force in the direction opposite to the conveying method to eliminate double feeding are also included in the category of the paper feeding roller.
The document reading apparatus may include a plurality of transport rollers that transport the document along the sheet transport path, and a registration roller that sends the transported document to the image reading unit at a predetermined timing.

The double feed detection means means for detecting double feed of originals when the originals are overlapped and fed.
Therefore, the double feed detection means may be an ultrasonic sensor or an optical sensor, or may be a mechanical displacement detection sensor that slides on the surface of the paper to be transported and is displaced according to the thickness of the paper. .

The image reading means means a means for scanning an image of a document and converting it into electronic image data, for example, a light source for irradiating light on the document, a mirror group for changing the optical path of reflected light reflected from the document, An image reading means of a reduction optical system composed of a lens for converging the reflected light whose optical path has been changed, a CCD for receiving the focused reflected light and converting it into an electrical signal, and the like.
Of course, the image reading means is not limited to such a reduction optical system, and for example, a contact image sensor may be used.

  The control unit means a microcomputer that controls the paper feed roller, the double feed detection unit, the image reading unit, and the paper discharge roller. For example, a CPU that performs arithmetic processing, a ROM that stores a control program, and various setting conditions are stored. RAM, a driver circuit for driving various drive units of the document reading device, an I / O port for inputting / outputting signals to / from each unit of the document reading device, and the like.

In the above document reading apparatus according to the present invention, when the control unit determines that double feeding has occurred, the document in the double feeding state is sandwiched between the discharge rollers to hold the document in that state, The document feeding from the sheet feeding unit to the sheet conveyance path may be stopped.
According to such a configuration, when it is determined that double feeding has occurred, paper feeding from the paper feeding unit to the paper transport path is stopped, and the multi-fed original is sandwiched between the paper ejection rollers and in this state. As a result, the user can easily and reliably distinguish a document that has been transported in a double-feed state and has not been subjected to image reading from other documents that have been image-read and previously discharged to the paper discharge unit. Can do.
As a result, the user can easily restore the arrangement order of the unconveyed originals remaining in the paper feeding unit by returning the originals sandwiched by the paper ejection rollers to the paper feeding unit, which is extremely convenient for the user. It becomes a high quality thing.

The document reading apparatus according to the above configuration in which the feeding of the document is stopped when it is determined that the double feeding has occurred and the document in the double feeding state is sandwiched between the paper discharge rollers is controlled by the control unit and is a desired one. The display unit further displays a message, and the control unit causes the display unit to display a message for returning the document held by the paper discharge roller to the paper supply unit when the document in the double feed state is held by the paper discharge roller. May be.
According to such a configuration, it is possible to clearly notify the user that the document sandwiched between the paper discharge rollers is a document to be returned to the paper feeding unit, and it is easy for the user to handle.

  Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

Embodiment An image forming apparatus equipped with a sheet through device (original reading device) (hereinafter abbreviated as “SPF”) according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an explanatory diagram schematically showing the overall configuration of an image forming apparatus equipped with an SPF according to an embodiment.

Overall Configuration and Operation of Image Forming Apparatus As shown in FIG. 1, an image forming apparatus 100 equipped with an SPF 1 according to an embodiment of the present invention can read image data obtained by reading a document conveyed by the SPF 1, or A monochrome image is formed on a predetermined recording sheet in accordance with image data transmitted from the outside.
The image forming apparatus 100 includes an automatic document transport unit 28, an SPF 1 including a first image reading unit 2 that reads an image on the front side of the document, and a second image reading unit 41 that reads an image on the back side of the document. The developing unit 4, the photosensitive member 5, the charger 6, the cleaner unit 7, the transfer unit 8, the fixing unit 9, the paper transport path 10, the paper feed tray 11, and the paper discharge tray 12.

The first image reading unit 2 of the SPF 1 is mainly composed of a light source unit 13, a mirror unit 14, and a CCD 15.
When reading the image on the front side of the document sent by the automatic document transport unit 28 by the document moving method, the image of the document is scanned and read while the light source unit 13 and the mirror unit 14 are stationary.
When the document is transported to a predetermined reading position by the automatic document transport unit 28, light is irradiated onto the document from the light source of the light source unit 13, and the reflected light reflected from the document is optically path-converted by the mirror unit 14. The reflected light is imaged on the CCD 15 and converted into electronic image data.
The specific structure and operation of the SPF 1 will be described in detail later.

The charger 6 is a charging means for uniformly charging the surface of the photoconductor 5 to a predetermined potential. In the image forming apparatus 100 according to the embodiment, the charger-type charger 6 is used. A roller-type or brush-type charger can also be used.
In this embodiment, a laser scanning unit (LSU) having laser irradiation units 16a and 16b and mirror groups 17a and 17b is used as the optical writing unit 3, but EL writing in which light emitting elements are arranged in an array. A head or an LED writing head can also be used.

The optical writing unit 3 employs a two-beam system including two laser irradiation units 16a and 16b in order to cope with high-speed printing processing, and the burden associated with increasing the irradiation timing is reduced.
Then, laser light is irradiated from the laser irradiation units 16a and 16b according to the input image data, and the photosensitive member 5 uniformly charged by the charger 6 is exposed through the mirror groups 17a and 17b. An electrostatic latent image corresponding to the image data is formed on the surface of the photoreceptor 5.

The developing device 4 disposed in the vicinity of the photoconductor 5 visualizes the electrostatic latent image formed on the surface of the photoconductor 5 with black toner.
A cleaner unit 7 disposed around the photoconductor 5 removes and collects toner remaining on the surface of the photoconductor 5 after development and image transfer.

The image forming apparatus 100 includes a control unit (not shown) that performs integrated control of the entirety.
The control unit receives signals from the CPU, a ROM that stores a control program executed by the CPU, a RAM that provides a work area to the CPU, a non-volatile memory that holds control data, and each unit detection unit of the image forming apparatus 100. The circuit includes an input circuit, an actuator that operates each unit drive mechanism of the image forming apparatus 100, a driver circuit that drives the motor, and an output circuit that drives the laser irradiation units 16a and 16b.

As described above, the electrostatic image visualized on the surface of the photoconductor 5 is applied by applying an electric field having a polarity opposite to that of the electrostatic image from the transfer unit 8 to the conveyed paper. Transferred onto recording paper.
For example, when the electrostatic image has a charge of (−) polarity, the polarity applied to the transfer unit 8 is (+) polarity.
The transfer belt 19 of the transfer unit 8 is stretched by a driving roller 20, a driven roller 21, and other rollers, and has a predetermined resistance value (for example, a range of 1 × 10 ⁹ to 1 × 10 ¹³ Ω · cm). ing.
An elastic conductive roller 22 that has conductivity and can apply a transfer electric field is disposed at a contact portion between the photosensitive member 5 and the transfer belt 19.

The electrostatic image (unfixed toner) transferred onto the recording paper by the transfer unit 8 is conveyed to the fixing unit 9 so that the unfixed toner is melted and fixed on the recording paper.
The fixing unit 9 includes a heating roller 23 and a pressure roller 24, and a heat source that makes the surface of the heating roller 23 a predetermined temperature (fixing temperature: approximately 160 to 200 ° C.) is built in the inner peripheral portion of the heating roller 23. Has been.
On the other hand, a pressure member (not shown) is arranged at both ends of the pressure roller 24 so as to come into pressure contact with the heating roller 23 with a predetermined pressure.
As a result, the unfixed toner on the conveyed recording paper is heated and melted by the heating roller 23 at the pressure contact portion (referred to as a fixing nip portion) between the heating roller 23 and the pressure roller 24, and the toner is removed at the pressure contact portion. Press on the recording paper to fix it on the recording paper.

The plurality of paper feed trays 11 are trays for storing recording sheets used for image formation, and are provided below the apparatus in the image forming apparatus 100 of the embodiment.
Since the image forming apparatus 100 of the embodiment is intended for high-speed printing processing, each of the paper feed trays 11 has a capacity capable of storing 500 to 1500 standard-size recording sheets.
In addition, a large-capacity paper feed cassette (LCC) 25 capable of storing a large amount of a plurality of types of recording paper and a manual feed tray 26 mainly used for printing of an irregular size are provided on the side surface of the image forming apparatus 100.

  The paper discharge tray 12 is disposed on the side opposite to the manual feed tray 26. However, instead of the paper discharge tray 12, a paper discharge paper post-processing device (stapling, punching, etc.) or multi-stage paper discharge is provided. The tray can be arranged as an option.

Configuration and Operation of SPF The SPF 1 mounted on the image forming apparatus 100 will be described with reference to FIGS. FIG. 2 is a cross-sectional view of an SPF (original reading apparatus) according to the embodiment, and FIG. 3 is an enlarged view of a main part of the SPF shown in FIG. 2, showing how the original is conveyed in a double feed state. FIG. 4 is a conceptual graph showing the correlation between the attenuation of ultrasonic waves caused by double feeding of originals and the electric energy level converted by the receiver, and FIG. 5 is a diagram of the control unit for controlling the SPF shown in FIG. FIG. 6 is a flowchart showing a control flow performed by the control unit.

  As shown in FIG. 2, the SPF 1 mounted on the above-described image forming apparatus 100 (see FIG. 1) includes a first platen glass 27 on which a document is placed when the document is read by the document fixing method. The image reading unit 2 mainly includes an automatic document conveyance unit 28 that is attached to the first image reading unit 2 so as to be opened and closed.

  The light source unit 13 of the first image reading unit 2 irradiates light, a reflector (not shown) that condenses light emitted from the light source 29 in a predetermined direction, and allows only reflected light from the original to pass through. The mirror unit 14 mainly includes a slit (not shown) and a first mirror 14a that changes the optical path of the reflected light that has passed through the slit by 90 degrees, and the mirror unit 14 further changes the reflected light reflected from the first mirror 14a by 180 degrees. The second mirror 14b and the third mirror 14c are configured.

  When the automatic document transport unit 28 is opened and closed by the user and a document is placed on the platen glass 27, the light source unit 13 and the mirror unit 14 respectively move to the home position when the document is read by the document fixing method. When a print request is made by the user, the light source unit 13 moves at a predetermined speed V in the sub-scanning direction, and at the same time, the mirror unit 14 moves at a speed of V / 2 in the sub-scanning direction. The reflected light from the original is guided to the CCD 15 through the imaging lens 30 while maintaining the optical path length to reach constant at all times.

  The automatic document conveyance unit 28 separates the document tray 31 on which the document bundle is placed, the pickup roller 32 that sends the document from the document bundle to the document conveyance path S1, and the document sent to the document conveyance path S1 one by one. The paper feed roller 33 and the separation roller 34 that convey downstream of the document conveyance path S1, the plural pairs of conveyance rollers 35 that convey the document along the document conveyance path S1, and the image on the front side of the document are read. Therefore, a first reading unit 36 provided in the document transport path S1, a second reading unit 37 provided on the downstream side of the first reading unit 36 for reading an image on the back side of the document, and a first A registration roller 38 that sends a document to the reading unit 36 at a predetermined timing and a pair of paper discharge rollers 40 a and 40 b that discharge the document whose image has been read to a paper discharge tray 39 are mainly configured.

The document tray 31 can be moved in the vertical direction. When a document bundle is placed, a sensor (not shown) detects this, and when a user requests printing, the document tray 31 moves upward, and the most of the document bundles. The document located on the upper side is sent out to the document conveyance path S1 by the pickup roller 32, and reaches the registration roller 38 through the paper feed roller 33, the separation roller 34, and a plurality of pairs of conveyance rollers 35.
After the original strikes the registration roller 38 to correct the skew, the original is again conveyed to the first reading unit 36 by the registration roller 38 at a predetermined timing.

  At this time, the light source unit 13 and the mirror unit 14 move to the home position of the document moving system shown in FIG. 2, and irradiate the document passing through the first reading unit 36 from the light source unit 13 while remaining stationary at the home position. Scan the original image.

  The original on which the image has been read is discharged to the paper discharge tray 39 via a pair of paper discharge rollers 40a and 40b. The side image is further read.

The automatic document transport unit 28 includes a second image reading unit 41 for the second reading unit 37 to read an image on the back side of the document by the document moving method.
The second image reading unit 41 includes a light source 42, a first mirror 43a, a second mirror 43b, a third mirror 43c, a fourth mirror 43d, an imaging lens 44, and a CCD 45.

  When a user requests double-sided scanning, light is emitted from the light source 42 to the document passing through the second reading unit 37, and reflected light reflected from the back surface of the document is reflected by the first mirror 43a and the second mirror. 43b, the third mirror 43c, the fourth mirror 43d, and the imaging lens 44, and then guided to the CCD 45.

By the way, when a document is sent out from a bundle of documents placed on the document tray 31 to the document transport path S1, normally, even if the document is sent to the document transport path S1 in a state of being overlapped, a separation roller is used. The multi-feed state is canceled by 34, and the sheet is conveyed one by one to the downstream side of the document conveying path S1 by the paper feed roller 33 as described above.
However, since the SPF 1 of the embodiment conveys the document at a high speed so as to correspond to the high-speed printing process, the possibility of double feeding cannot be denied even if the separation roller 34 is provided.
Therefore, the SPF 1 of the embodiment is provided with a double feed detection sensor 46 as a double feed detection means on the downstream side of the paper feed roller 33 and the separation roller 34. The double feed detection sensor 35 includes a transmitter 47 that transmits ultrasonic waves and a receiver 48 that receives the ultrasonic waves transmitted from the transmitter 47 and converts the ultrasonic waves into electrical energy.

As shown in FIG. 3, when the original document Da and the original document Db are conveyed in a double feed state in which they overlap each other, the ultrasonic wave transmitted from the transmitter 47 is generated by the overlap of the original documents Da and Db. It is greatly attenuated by a slight air layer, received by the receiver 48, and converted into electrical energy.
Therefore, as shown in FIG. 4, by comparing the level of the electrical energy converted by the receiver 48 with a predetermined threshold, the documents Da and Db are normally conveyed one by one, or FIG. It can be detected whether it is conveyed in the double feed state as shown in FIG.

Here, the structure of the control part which controls SPF1 is demonstrated based on FIG.
As shown in FIG. 5, the control unit 49 that controls the SPF 1 includes a CPU 50 that performs arithmetic processing, a ROM 51 that stores a control program, a RAM 52 that stores various setting conditions, and an I that performs input and output of signals with various sensors of the SPF 1. / O port 53, and a driver circuit 54 for driving various drive units of SPF1.

Hereinafter, a control flow in which the control unit 49 controls the SPF 1 will be described with reference to FIG. In addition, please refer FIG. 2 suitably about each part of SPF1 quoted in description of the following control flows.
As shown in FIG. 6, when the user makes a reading request for the document in step 1 to the standby SPF 1, the process proceeds to step 2 to determine whether or not a document is placed on the document tray 31. If it is determined that the document is placed on the document tray 31, the process proceeds to step 3 to start conveying the document.
After starting the conveyance of the original in step 3, the process proceeds to step 4 and it is determined whether or not the double feed detection sensor 46 detects the double feed of the original. Specifically, as described above, it is determined whether or not the level of the electric energy converted by the receiver 48 is lower than a predetermined threshold (one level).

If no double feed of the original is detected in step 4, the process proceeds to step 5 to perform the original reading process, and then proceeds to step 6 to discharge the original to the paper discharge tray 39, and there is an original to be read next. (Step 7).
If it is determined in step 7 that there is a document to be read next, the process returns to step 3 to start transporting the next document, and if it is determined that there is no document to be read next, the series of flow is finished and a standby state is entered. Return.

On the other hand, if the document double feed is detected in step 4, the process proceeds to step 8 to stop the document reading process for the multi-feed document, and proceeds to step 9 to continue the conveyance of the multi-feed document. The double-fed original is pinched at 40b (step 10).
When the multi-fed original is pinched in step 10, the process proceeds to step 11 and a message is displayed on the display unit to prompt the user to return the original held by the paper discharge roller to the original tray. It is determined whether or not the double feed document held between 40a and 40b has been removed.

  If it is determined in step 12 that the multi-fed originals sandwiched between the paper discharge rollers 40a and 40b have been removed, the process proceeds to step 13 to display a message prompting the user to resume original reading by pressing the start key. It is determined whether or not the button has been pressed (step 14). If it is determined in step 14 that the start key has been pressed, the process returns to step 3 to resume the conveyance of the document.

In the above control flow, the conveyance of the original document, the document reading process, and the delivery of the next original document are started after the completion of the conveyance, the document reading process or the paper ejection for the previously conveyed document. It is also possible to control so as to convey the document continuously one after another without waiting.
In this case, when a double-fed original is detected, the original reading process and paper discharge are completed for the original that has been fed first and is transported normally, and the next original remains on the original tray 31. In this case, control is performed so as to stop the conveyance of the document.

1 is an explanatory diagram schematically showing an overall configuration of an image forming apparatus equipped with an SPF (original reading apparatus) according to an embodiment of the present invention; FIG. It is sectional drawing of SPF (original reading apparatus) by an Example. FIG. 3 is an enlarged view of a main part of the SPF shown in FIG. 2 and shows a state in which a document is conveyed in a double feed state. FIG. 6 is a conceptual graph showing a correlation between attenuation of ultrasonic waves caused by double feeding of originals and an electric energy level converted by a receiver. It is a block diagram which shows the structure of the control part which controls SPF shown by FIG. It is a flowchart figure which shows the control flow of a control part.

Explanation of symbols

1 ... SPF (original reading device)
DESCRIPTION OF SYMBOLS 2 ... 1st image reading part 3 ... Optical writing unit 4 ... Developing device 5 ... Photoconductor 6 ... Charger 7 ... Cleaner unit 8 ... Transfer unit 9 ... Fixing unit 10: paper transport path 11 ... paper feed tray 12, 39 ... paper discharge tray 13 ... light source unit 14 ... mirror unit 14a, 43a ... first mirror 14b, 43b ... Second mirror 14c, 43c ... Third mirror 15, 45 ... CCD
16a, 16b ... Laser irradiation parts 17a, 17b ... Mirror group 19 ... Transfer belt 20 ... Drive roller 21 ... Follower roller 22 ... Elastic conductive roller 23 ... Heating roller 24 ... Pressure roller 25 ... Large-capacity paper cassette 26 ... Bypass tray 27 ... Platen glass 28 ... Automatic document transport unit 29,42 ... Light source 30,44 ... Image formation Lens 31 ... Document tray 32 ... Pickup roller 33 ... Paper feed roller 34 ... Separation roller 35 ... Conveying roller 36 ... First reading unit 37 ... Second reading unit 38 ..Registration rollers 40a, 40b... Discharge roller 41... Second image reading unit 43d... Fourth mirror 46 .. double feed detection sensor 47. Container 49 ・..Control unit 50 ... CPU
51 ... ROM
52 ... RAM
53 ... I / O port 54 ... Driver circuit 100 ... Image forming apparatus Da, Db ... Original S1 ... Original conveyance path

Claims (7)

  When paper loaded in the paper feed section is fed to the paper transport path, it is determined whether or not double feed has occurred in the paper fed to the paper transport path, and it is determined that multi-feed has not occurred Performs a predetermined process on the paper and then discharges the paper to the paper discharge section by the paper discharge roller. If it is determined that a multi-feed has occurred, the multi-feed state is not performed on the paper. A paper transport method that continues the transport of paper and sends it to the paper output section.   The paper transport method according to claim 1, wherein when it is determined that double feeding has occurred, paper feed from the paper feed unit to the paper transport path is stopped.   3. The paper transport method according to claim 2, wherein the paper that has been transported in the double feed state is held by the paper discharge roller and held in that state.   When it is determined that double feeding has occurred in the fed paper and there is paper in the paper transport path that is fed before the paper that has been double fed, The sheet conveying method according to any one of claims 1 to 3, wherein a predetermined process is performed and the sheet is discharged to a sheet discharge unit.   A paper feed unit for loading originals, a paper feed roller for feeding the originals stacked on the paper feed unit to the paper conveyance path, and a document provided in the middle of the paper conveyance path to be fed to the paper conveyance path Double feed detection means for detecting the double feed of the original, an image reading means for reading the image of the conveyed original, a paper discharge roller for discharging the original to the paper output section, a paper feed roller, A control unit that controls the detection unit, the image reading unit, and the paper discharge roller. The control unit drives the paper feed roller to feed the original to the paper transport path, and overlaps the original fed to the paper transport path. Whether or not feeding has occurred is determined by the double feeding detection means. If it is determined that double feeding has not occurred, the image reading means executes image reading of the document and drives the discharge roller to discharge the document. If it is determined that double feeding has occurred, the original Document reading apparatus for feeding while the conveyance of the document continues multifeed state without executing the reading of the image to the sheet discharge unit.   If the control unit determines that double feeding has occurred, the document in the double feeding state is held between the paper discharge rollers and held in that state, and the document is fed from the paper feeding unit to the paper conveyance path by the paper feeding roller. The document reading apparatus according to claim 5, wherein the sheet feeding is stopped.   The display unit further includes a display unit that is controlled by the control unit and displays a desired message. The control unit returns the original document held by the paper discharge roller to the paper supply unit when the double-fed original document is held by the paper discharge roller. The document reading device according to claim 6, wherein the message is displayed on the display unit.

Images